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Situation Calculus
The situation calculus is a logic formalism designed for representing and reasoning about dynamical domains. It was first introduced by John McCarthy in 1963. The main version of the situational calculus that is presented in this article is based on that introduced by Ray Reiter in 1991. It is followed by sections about McCarthy's 1986 version and a logic programming formulation. Overview The situation calculus represents changing scenarios as a set of first-order logic formulae. The basic elements of the calculus are: *The actions that can be performed in the world *The fluents that describe the state of the world *The situations A domain is formalized by a number of formulae, namely: *Action precondition axioms, one for each action *Successor state axioms, one for each fluent *Axioms describing the world in various situations *The foundational axioms of the situation calculus A simple robot world will be modeled as a running example. In this world there is a single robot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises in a topic-neutral way. When used as a countable noun, the term "a logic" refers to a logical formal system that articulates a proof system. Formal logic contrasts with informal logic, which is associated with informal fallacies, critical thinking, and argumentation theory. While there is no general agreement on how formal and informal logic are to be distinguished, one prominent approach associates their difference with whether the studied arguments are expressed in formal or informal languages. Logic plays a central role in multiple fields, such as philosophy, mathematics, computer science, and linguistics. Logic studies arguments, which consist of a set of premises together with a conclusion. Premises and conclusions are usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumscription (logic)
Circumscription is a non-monotonic logic created by John McCarthy to formalize the common sense assumption that things are as expected unless otherwise specified. Circumscription was later used by McCarthy in an attempt to solve the frame problem. To implement circumscription in its initial formulation, McCarthy augmented first-order logic to allow the minimization of the extension of some predicates, where the extension of a predicate is the set of tuples of values the predicate is true on. This minimization is similar to the closed-world assumption that what is not known to be true is false. The original problem considered by McCarthy was that of missionaries and cannibals: there are three missionaries and three cannibals on one bank of a river; they have to cross the river using a boat that can only take two, with the additional constraint that cannibals must never outnumber the missionaries on either bank (as otherwise the missionaries would be killed and, presumably, eate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1963 Introductions
Events January * January 1 – Bogle–Chandler case: Commonwealth Scientific and Industrial Research Organisation scientist Dr. Gilbert Bogle and Mrs. Margaret Chandler are found dead (presumed poisoned), in bushland near the Lane Cove River, Sydney, Australia. * January 2 – Vietnam War – Battle of Ap Bac: The Viet Cong win their first major victory. * January 9 – A total penumbral lunar eclipse is visible in the Americas, Europe, Africa, and Asia, and is the 56th lunar eclipse of Lunar Saros 114. Gamma has a value of −1.01282. It occurs on the night between Wednesday, January 9 and Thursday, January 10, 1963. * January 13 – 1963 Togolese coup d'état: A military coup in Togo results in the installation of coup leader Emmanuel Bodjollé as president. * January 17 – A last quarter moon occurs between the penumbral lunar eclipse and the annular solar eclipse, only 12 hours, 29 minutes after apogee. * January 19 – Soviet spy Gheorghe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The ACM
The ''Journal of the ACM'' is a peer-reviewed scientific journal covering computer science in general, especially theoretical aspects. It is an official journal of the Association for Computing Machinery. Its current editor-in-chief is Venkatesan Guruswami. The journal was established in 1954 and "computer scientists universally hold the ''Journal of the ACM'' in high esteem". See also * ''Communications of the ACM ''Communications of the ACM'' is the monthly journal of the Association for Computing Machinery (ACM). It was established in 1958, with Saul Rosen as its first managing editor. It is sent to all ACM members. Articles are intended for readers wi ...'' References External links * Publications established in 1954 Computer science journals Association for Computing Machinery academic journals Bimonthly journals English-language journals {{compu-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Transactions On Artificial Intelligence
The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for promoting natural sciences and mathematics and strengthening their influence in society, whilst endeavouring to promote the exchange of ideas between various disciplines. The goals of the academy are: * to be a forum where researchers meet across subject boundaries, * to offer a unique environment for research, * to provide support to younger researchers, * to reward outstanding research efforts, * to communicate internationally among scientists, * to advance the case for science within society and to influence research policy priorities * to stimulate interest in mathematics and science in school, and * to disseminate and popularize scientific information in various forms. Every year, the academy awards the Nobel Prizes in physics and chemis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Calculus
The event calculus is a logical language for representing and reasoning about events and their effects first presented by Robert Kowalski and Marek Sergot in 1986. It was extended by Murray Shanahan and Rob Miller in the 1990s. Similar to other languages for reasoning about change, the event calculus represents the effects of actions on fluents. However, events can also be external to the system. In the event calculus, one can specify the value of fluents at some given time points, the events that take place at given time points, and their effects. Fluents and events In the event calculus, fluents are reified. This means that they are not formalized by means of predicates but by means of functions. A separate predicate is used to tell which fluents hold at a given time point. For example, \mathit(on(box,table),t) means that the box is on the table at time ; in this formula, is a predicate while is a function. Events are also represented as terms. The effects of events ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Problem
In artificial intelligence, the frame problem describes an issue with using first-order logic (FOL) to express facts about a robot in the world. Representing the state of a robot with traditional FOL requires the use of many axioms that simply imply that things in the environment do not change arbitrarily. For example, Hayes describes a " block world" with rules about stacking blocks together. In a FOL system, additional axioms are required to make inferences about the environment (for example, that a block cannot change position unless it is physically moved). The frame problem is the problem of finding adequate collections of axioms for a viable description of a robot environment. John McCarthy and Patrick J. Hayes defined this problem in their 1969 article, ''Some Philosophical Problems from the Standpoint of Artificial Intelligence''. In this paper, and many that came after, the formal mathematical problem was a starting point for more general discussions of the difficulty of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SLD Resolution
SLD resolution (''Selective Linear Definite'' clause resolution) is the basic inference rule used in logic programming. It is a refinement of resolution, which is both sound and refutation complete for Horn clauses. The SLD inference rule Given a goal clause, represented as the negation of a problem to be solved : \neg L_1 \lor \cdots \lor \neg L_i \lor \cdots \lor \neg L_n with selected literal \neg L_i , and an input definite clause: L \lor \neg K_1 \lor \cdots \lor \neg K_m whose positive literal (atom) L\, unifies with the atom L_i \, of the selected literal \neg L_i \, , SLD resolution derives another goal clause, in which the selected literal is replaced by the negative literals of the input clause and the unifying substitution \theta \, is applied: (\neg L_1 \lor \cdots \lor \neg K_1 \lor \cdots \lor \neg K_m\ \lor \cdots \lor \neg L_n)\theta In the simplest case, in propositional logic, the atoms L_i \, and L \, are identical, and the unifying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negation As Failure
Negation as failure (NAF, for short) is a non-monotonic inference rule in logic programming, used to derive \mathrm~p (i.e. that ~p is assumed not to hold) from failure to derive ~p. Note that \mathrm ~p can be different from the statement \neg p of the logical negation of ~p, depending on the completeness of the inference algorithm and thus also on the formal logic system. Negation as failure has been an important feature of logic programming since the earliest days of both Planner and Prolog. In Prolog, it is usually implemented using Prolog's extralogical constructs. More generally, this kind of negation is known as weak negation, in contrast with the strong (i.e. explicit, provable) negation. Planner semantics In Planner, negation as failure could be implemented as follows: :''if'' (''not'' (''goal'' p)), ''then'' (''assert'' ¬p) which says that if an exhaustive search to prove p fails, then assert ¬p. This states that proposition p shall be assumed as "not true" in an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluent Calculus
The fluent calculus is a formalism for expressing dynamical domains in first-order logic. It is a variant of the situation calculus; the main difference is that situations are considered representations of states. A binary function symbol \circ is used to concatenate the terms that represent facts that hold in a situation. For example, that the box is on the table in the situation s is represented by the formula \exists t . s = on(box,table) \circ t. The frame problem is solved by asserting that the situation after the execution of an action is identical to the one before but for the conditions changed by the action. For example, the action of moving the box from the table to the floor is formalized as: : State(Do(move(box,table,floor), s)) \circ on(box,table) = State(s) \circ on(box,floor) This formula states that the state after the move is added the term on(box,floor) and removed the term on(box,table). Axioms specifying that \circ is commutative and non-idempotent are necessary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John McCarthy (computer Scientist)
John McCarthy (September 4, 1927 – October 24, 2011) was an American computer scientist and cognitive scientist. He was one of the founders of the discipline of artificial intelligence. He co-authored the document that coined the term "artificial intelligence" (AI), developed the programming language family Lisp (programming language), Lisp, significantly influenced the design of the language ALGOL, popularized time-sharing, and invented Garbage collection (computer science), garbage collection. McCarthy spent most of his career at Stanford University. He received many accolades and honors, such as the 1971 Turing Award for his contributions to the topic of AI, the United States National Medal of Science, and the Kyoto Prize. Early life and education John McCarthy was born in Boston, Massachusetts, on September 4, 1927, to an Irish people, Irish immigrant father and a Lithuanian Jewish immigrant mother, John Patrick and Ida (Glatt) McCarthy. The family was obliged to relocat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Problem
In artificial intelligence, the frame problem describes an issue with using first-order logic (FOL) to express facts about a robot in the world. Representing the state of a robot with traditional FOL requires the use of many axioms that simply imply that things in the environment do not change arbitrarily. For example, Hayes describes a " block world" with rules about stacking blocks together. In a FOL system, additional axioms are required to make inferences about the environment (for example, that a block cannot change position unless it is physically moved). The frame problem is the problem of finding adequate collections of axioms for a viable description of a robot environment. John McCarthy and Patrick J. Hayes defined this problem in their 1969 article, ''Some Philosophical Problems from the Standpoint of Artificial Intelligence''. In this paper, and many that came after, the formal mathematical problem was a starting point for more general discussions of the difficulty of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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